Interstitial Cystitis (IC) is a chronic bladder syndrome characterized by urinary urgency, frequency, nocturia pain and sterile urine. Although inflammation is not a universal characteristic of biopsies from IC patients, it seems that inflammation underline all major bladder pathologies including malignancy and represents a defense reaction to injury caused by physical damage, chemical substances, microorganisms or other gents. Indeed, areas of bladder inflammation are found in bladder disease including carcinoma, during chronic implantation of catheters, and an integrative part of bladder responses to intravesical Bacillus Calmette-Guerin (BCG). Although BCG has been proposed as a promising option for treatment of IC its mechanisms of action is not completely known. One of the theories is that intravesical BCG may be effective in treating by correcting an aberrant immune imbalance in the bladder, leading to long-term symptomatic improvement. It remains to be determined the nature of this immune imbalance. As nuclear factor kappaB (NFkappaB) has been described to modulate both bladder inflammation and the effects of BCG therapy, it is fair to propose, as a central hypothesis, that intravesical BCG leads to activation of NFkappaB and translation of pro- and anti-inflammatory genes that control both the immune and inflammatory system. The long-range goals of this application are to determine the gene networks involved in bladder responses to BCG therapy. To meet these goals, we will use the mouse as a vehicle for understanding basic biological questions regarding BCG and to permit rigorous control of experimental design. Transgenic mice with reporter genes expressed specifically on endothelial cells (Tie2-LacZ) and on promoter elements responsive to NFkappaB (p105-LacZ and p65-LacZ) will be used to address our hypothesis. In addition, the appropriate use of micro array technology combined with subtractive hybridization (SSH) will identify key molecules and mechanisms involved in the transition between acute and chronic inflammation in individual bladder layers. To address our central hypothesis, Aim 1 will quantify the time course alterations in bladder morphology as a consequence of acute and chronic intravesical BCG therapy. Aim 2 will test the hypothesis that NFkB plays a central role on BCG-induced bladder inflammation and Aim 3 will test the hypothesis that acute and chronic instillation of BCG induce a differential gene regulation in bladder mucosa and detrusor muscle. For this purpose, we will use micro array technology combined with suppression subtractive hybridization (SSH) to select bladder mucosa- and detrusor specific genes. Following target validation of SSH-selected genes, a custom array will be developed. This micro array will be used to determine how the bladder transcriptome is altered by BCG therapy.